Still in the planning phase of a DIY raft project, the alpacka rafts are a touch spendy for me, and I think it could be made lighter, plus DIY is always a good time even if I fail.

Intent: hike in lake, gentle river fishing raft.
weight: <3 lbs

looking for design/construction/material ideas, anecdotal included. (is a more square aft/stern worthwhile, symmetrical/asymmetrical, is wider in the middle worth the weight/cost, valve recommendations, is some form of an inflatable seat worth the hassle?)

I asked "Alpacka Raft LLC" assuming that was the owner of this forum before posting (if i was incorrect please let me know), I didn't want to be out of line.

If I came across as such I apologize.

I posted here because I figured people that actually know something about rafts could provide some insight into things I wouldn't have thought of, you guys take rafts into situations I wouldn't ever want to be in.

Schooled and employed as an engineer, Alaskan by birth... I like to make my own stuff where I can.

Hi, uncoolperson did contact us, and... well, "he's cool." We're happy to say Alpacka started as a DIY raft, and we're big believers in our boats, but Alpackas certainly aren't the best boat for all packrafters - and the freedom to tinker with, mod, and build gear is something we love about packrafting.

Thanks for your vigilance on our behalf, though, AeroNautiCal! (Tip of hat). In this case, UCP has posted with our blessing. Cheers! -Alpacka

I toyed with this concept a few years ago (although I was initially out to make the "ultimate" thick, lightweight lilo for river sledding), and then found out about Alpacka's, and thought a lot about making a similar raft. The biggest problem I had with both these projects was finding an appropriate valve, and being able to attach it. There was, at that stage another raft available semi-commercially, which was cheaper, but it just didn't compare. In the end I just bit the bullet and bought an Alpacka, and now own 2.

I reckon that for all the buggerizing around designing it, and trying to seal the seams, you're better to spend time making other gear! Also, the type of fabric used on the Alpackas is like nothing else you'll find in the general outdoor industry, and is unbelievably tough (as in almost unpuncturable). Make one out of nylon packcloth etc, and you wouldn't be much better off than having a Sevylor, but for a lot more work.

I can't help but feel that even if you made a raft and got around these problems, you'd be disappointed - packs/sleeping bags etc are also easy to make in comparison - and there's now a lightweight raft available from Alpacka, isn't there?

Slorry to be negative about it, particularly from someone wo is happy to make almost anything.............

which a poorly (testing worst case) made seam (two pieces with a strip on the opposite side to get the sealable to sealable mate) held up to almost 10psi of air (didn't test higher, our testing setup failed before it did). at about 6 oz a sq yard, should come up just shy of 36 oz of fabric.... doesn't look like I'm hitting my sub 3 lbs. Also held up to the very scientific "punch it with a screwdriver under pressure test" and "rub it on the sidewalk a bunch test".

I do understand that anything I make will most likely be sub alpacka quality, that's what happens when I pick up an idea with no background... gotta try though, even if I know it'll end in failure.

Alpackas (from what i've read) rock, I get this... I don't expect to even come close to quality and materials, it's just fun picking up a pre-summer project every now and again (reminding myself about that RC plane, fly tying stuff, ammo reloading stuff, box of legos, etc... hiding away in some closet).

I'm also not trying to copy the Alpacka idea/design, I came here looking for general raft ideas and suggestions. If anything I'm copying the idea/intent behind the curtis raft, when water is moving I do my best to keep out of it's way.

A couple ideas, suggestions, etc. from left field for you. Have no idea if they would work, but I like thinking outside the box too. Best ideas are always those that are so radically different from convention...

If making it similar in shape and sitting position to an Alpacka, and not tackling rough whitewater, maybe reduce the size of the air-chamber in front? Even with a bike or pack in front, they are rear-heavy and to me anyway the amount of air in front is not accomplishing much except for bouncing off rocks and not getting sucked into holes. This might save on some material and thus weight. Maybe not even need the air chamber to go all the way around, ie just have the front be one piece of the material, or maybe just have the chamber be more rectangular shape up front, 1" thick to bounce off things instead of the full diameter circle it is all around.

This could be cold, literally, but depending on what your intended use is, maybe lose the full floor, rig some kind of strapping to sit on and rest legs on?

Alpackas have two nozzles, one for bag inflation, second for finishing touches of manual inflation. Maybe combine the two? Save however many ounces of weight one of those nozzles is.

Thanks john, I was planning to go with 12 inch dia all around. Less math for me that way.

A number of the lakes I plan to take this too will still have small chunks of ice floating around come aug, it's be a touch too cold for me.

I was thinking of going symmetrical (for ease of design) front and back with a 150 degree or so angle at the nose. This is one of the things I was wondering about, does a flat bow change much for low speed rafting around a calm lake?

If your raft is going to be generally similar to an Alpacka, you might want to find a way to add buoyancy in the stern, since most of one's weight tends to be in the stern. You could even just add a little length, and put a back-support spacer that pushes you a bit toward the middle, thus keeping your constant dia. tube?

I looked at fabric you mentioned, and would be interested in some subsequent feedback about how heat sealable it turns out to be, as there are some other uses I may have for it should it work well. Another suggestion for making the seams are to sew them, and then use Sheri's favorite tyvek tape to seal them, and/or aquaseal, or both.

The valve you found is the same as the best one that I was able to find in Oz, but I decided it was too heavy for my original application in an ultralight "super-lilo".

As to raft design, a lower front, and more air at the back would make a more useable raft if not going to be used for packrafting, as the Alpacka's handle a hell of a lot better with a pack across the front, and are otherwise rather "arse" heavy.

Have fun, and hopefully you won't end up being like me with some such projects (eg my original lilo/raft thoughts), where you expend a zillion kilojoules of mental effort, looking for things that are generally not available to the public, and then realise that someone has already "been there and done that", and that had you worked in your day jobfor the equivalent time earning money, the Alpacka version would have been cheap! (accepting that making something yourself DOES make one feel rather clever!)

About 15 years ago I made a half dozen packrafts. The first one lasted from 1993 to 1999 on many Alaskan hellbike trips and Wilderness Classic adventure races as well as this run in Patagonia (http://www.youtube.com/watch?v=9nLdtfqH8S4). The others actually sold to other folks desperate for boats.

Neither handy, manually skilled, nor an enthusiastic DIY-er, I just needed boats!... so each one took about 24 hours of work, too much glue huffing, and a a bunch of burned fingers. But it was very satisfying to have a serviceable boat....it weighed 3 pounds 4 ounces and was as long as a Llama on the inside. It was based on the Sherpa raft design, upturned bow, upturned stern, two chambers, ten inch tubes.

A good hand iron (like for ironing clothes) was the most important piece of equipment. "Good" means heavy so it held heat a long time. And a good roller to push the heated fabric together immediately.

The Curtis Design boat is sub-3 pound and a proven flatwater design -- do you have one of those to model your boat after?

Hig, I'll have to work on a way to get the CG of me to the CG of the raft, thanks for the idea.

Andrew, sealable side to sealable side than iron rubbed on it a few times seemed to hold up okay, not sure about my trust for tyvek, I've used the suits at work and play (easy paintball snow camo) and they never held up well... is the tape stronger?

Roman, so you ironed then pressed them together? I was planning to just iron together... does pressing together after ironing provide any benefit? Also I don't have access to a curtis raft, just a few pictures lying around online and a rough idea.

my hand ironed test piece still hasn't come apart by any simple manual means, though I'm not much of a tuff guy... maybe I need to do more than just pull on it.

Well, depends on what you mean by "permanent." The adhesive appears to have good longevity, and sunlight appears to cure it onto urethane, but the tape is vulnerable to abrasion / mechanical damage. It all depends on what kind of usage & longevity you're going for.

Heat sealing around curves wouldn't be that easy. Bail out solution may be to fold seem flat, and oversew it, and then seal the seam, either with tyvek on the inside, or a strip of your fabric ironed on (like commercial seam sealing), and lastly consider aquaseal if needed on the outside.

Glad you're adding up the various costs - it will be interesting to see how it goes, and, given the forum interest, there had better be pictures at the end.............

Hand-stitch edge-to-edge using a "baseball stitch" followed by a coat of Aquaseal on both sides. There's a diagram of a baseball stitch here: http://www.perestroika.ca/html2/vest/handstitching.php They say the baseball stitch is "decorative", but it can be extremely useful.

Hand stitching takes a long time, and edge-to-edge sounds weak. But doing it this way means you have complete control, and can avoid all the wrinkles and folds that are very difficult to avoid otherwise. And my experience is that it's quite strong, as long as you use fairly close stitch spacing (I think mine were a couple mm per stitch?) and keep the tension even so there are no puckers that can focus stress and start tearing threads. I did 2 feet of field repair like this, and had no leaks on the first iteration. The boat has only been used for about 2 weeks of travel since (in about 11 months), but so far the repair seems pretty stable. I think that if I were making a major mod (or taking on your more ambitious project) I'd consider doing this at least for the most difficult seams.

And of course you could glue on a thin strip of additional fabric for added strength after getting the stitch in place. On the other hand I like the way the seam is totally visible, so you can see if there's any peeling or whatever...

This sort of hand stitching does take a bit of practice, but you'd have plenty by the time you finished your raft!

went with a strip of the material along the inside ironed on... didn't turn out all that pretty, screwed up a few places along the inside of the raft where everything comes together. the heat sealable side doesn't adhere very well to the not heat sealable side, lots of aqua seal to fix that mistake.

then lots of aqua seal along my normal seams (which were leaky).... and I'm still tracking down 2-3 more small leaks.

learning experience, I'll probably do this again this winter after I've learned all my lessons.

Another tape option is to use the double sided tape used by sail makers over sewn seams , and use it to stick a strip of nylon over the seam. I
ve also fiddled with sail repair tape (basically adherent rip stop), but have only used it for sealing seams on stuff sacks, which seems to work OK, but not sure how truly watertight/airtight it is. It sticks pretty well to the urethane fabric of my Alpacka too. Last suggestion is to use a urethane based glue to glue strips of fabric over the seams.

One of the great outcomes from this particular post is that it becomes obvious how much R & D goes into making a product like an Alpacka.

used the biggest bass guitar string I could find to help get the curve right, and a big chunk of wood to help as my backing while ironing (next time curved piece of wood at the approx diameter and width is necessary).

add another my guess easy $100 materials and 20 hours build time plus $50-$100 hardware for the next build.

Lessons learned, think through and maybe non permanent mock up the build prior to building... make sure my methods will work.
This proved a problem working out the seal that turns all the flat pieces into tubes, I connected everything together hoping to fold then seal up.... that didn't work had to make those seals in tension rather than shear (I was warned about the seal style, but i was stuck). [see attached image]

Work out a better idea than a piece of wood and a clothing iron, didn't seal the pieces together nicely, fought with that for way too long.

Figure out supply of aquaseal and the fancy accelerator, sure the company's headquarters are in my town.... but they're closed on weekends.
Also, get more brushes, nothing gets it off the one brush in the package.

If my job was more secure (does anybody have one of those right now?) I'd probably whip out the visa card and get me an alpacka for the summer... saddly it aint. Heck, my resume is all over the place right now.

Good try UCP - it was a fun forum to follow, and I have respect for anyone who is prepared to tackle such a project, even though it may be seen as "reinventing the wheel" so to speak. It does make Roman's production of 6 Sherpa's back in the 90s something of a feat though. Outside of things that are meant to float (or fly), I think DIY has a great potential, as much of the stuff on the market is designed primarily to last "long" enough, rather than to minimise weight, whereas most DIY gear can be made light, and repaired without any issue.

Suggest that regardless of your work longevity, you seriously consider biting the proverbial bullet and buying a raft . They are fantastic fun, and you only live once. (or think of it as earning $10/hr doing something comparatively menial for 2 weeks = 1 raft..................).

summerrun, I did the 1st floorless boat experiment for Alpacka. Depending on the boat you want to convert, it's... well, I guess "possible but depends on what you're after and what you're converting." And keeping in mind there's an Alpacka experiment -but- with an unknown timespan or outcome going. There would definitely be some unknowns in DIY. How into this project are you?

Shaggy: What result for your floorless ventures? I'm toying with the idea of trying to do that with an Explorer with the goal of getting something along the lines of the water master and water strider rafts, but with less weight. (I would like to keep it under 15 lbs). Thought is to remove the FE floor, then reinforce and glue in an 18"-20" floor material shelf just above the load water line at the rear to support the seat. Then modify the newer rowing frame so it was a bit longer and a snug side to side fit. Install it in a similar raised, above LWL position using heavy duty strap attachments as needed and a beefed up front cross bar for a foot rest. The rear cross piece would be velcro strap attached to the underside front of the seat shelf for extra support. The snug frame would give the tubes side to side support and help hull rigidity. Maybe put in some cross webbing in the front 8" as support for a dry bag. Think it would work? Any thoughts on this approach would be appreciated.

Also, if Alpacka is planning on coming out with something like this fairly soon I'd probably wait and get one of theirs. Seems to me the ideal would be FE-like but about 10" -12" longer and 6" wider with more buoyancy at the rear where the weight is, and maybe a bit bigger tubes all round to make up for the buoyancy loss from the floor removal. A tougher rowing frame/system would be needed as well.

Seems like the trick, if you don't have a full floor, is to replace the shear strength and tension provided by the floor. Sounds like your frame mod might achieve that? It sounds like the sort of thing that would have a really rough rough draft...

Hig: Just noodling it out, it seems the frame mod + retaining 16" or so of raised but attached floor at the rear and 8" at the front (maybe with a couple of sewn in cross webs for lateral strength) would be enough support for the tubes. That would leave a floor opening of about 28" x 15" which is a bit tight but should be enough to allow the use of kickboat fins and stand up wading in slow water. For wading safety while casting, you would want the raft to rotate easily around your legs and quickly weather cock in moving water so that most of the hull was always downstream and parallel to the current.